In some satellite communications systems, satellite-based communications nodes, such as low-earth orbit (LEO) satellites, communicate with one another and with terrestrial communications nodes, such as gateway terminals, wireless devices, and tracking, telemetry, and control (TT&C or TTAC) stations.
LEO satellites typically utilize different types of on-board antennas to communicate with different types of communications nodes within the satellite communications system. For example, a satellite-based phased-array antenna can be used for communications with earth-based wireless devices such as satellite telephones and pagers, whereas an omni-directional antenna is often used for communications with TT&C stations during the initial ascent phase and in a temporary orbital parking phase prior to the satellite's deployment to its final orbit. Parabolic antennas, and other types of antennas, are often used for other communications links, such as for inter-satellite links (cross-links) to and from neighboring satellites and for feeder links to and from gateway terminals that link the satellite signals with wired communications infrastructure such as terrestrial communications networks.
There are several disadvantages to using antennas of different types on-board a communications satellite. These include: additional mass and volume; additional cost and time to design, build and/or purchase, integrate, test, launch, and maintain the satellite's antenna systems; additional complexity of the satellite; additional power consumption; and the difficulties in antenna system layout on the satellite to avoid the situation where one antenna can block communications signals being sent to or from another antenna on the satellite.
Accordingly, there is a significant need for systems and methods that can reduce the number and types of separate antennas required on a communications node such as a satellite.
There is also a significant need for systems and methods that can operate a single phased-array antenna on a satellite-based communications node in more than one mode.
There is also a significant need for a satellite-based communications system that can communicate with different types of terrestrial communications nodes, using at least two different modes of operation, one mode having a diffused beam pattern and using a communications channel having a relatively low bandwidth, and another mode having a focused beam pattern and using a communications channel having a relatively high bandwidth.
There is a further significant need for a satellite-based communications system having a phased-array antenna that can communicate using at least two different modes of operation, in which at least one data structure, including phased-array antenna data such as antenna coefficients, is stored in an on-board computer-readable medium or memory and is used to control the antenna to operate in the at least two modes.